68post

No, it could pulling it into the exhaust and causing a pop, but not necessarily into the cylinder itself.

BakedPotato65

Well I installed a new MSD Pro Billet Ready to Run distributor and a MSD Blaster 2 coil to replace the original ignition. I did not make any adjustments to the distributor, such as timing curve. The car started right up and sounded a lot stronger than it used to. I took it for a drive today and experienced some weird things, first was that the car died when I had to make a quick stop at a red light, and when I went to start it back up it took quite a bit of cranking for it to fire up. I'll probably just have to adjust the rear float bowl to fix it. Throughout the drive I noticed the exhaust popping was still present so it's something other than ignition, I'm going to reset the valve lash next. The car seemed to run great, but after a few moderate to aggressive accelerations the car began to run funny. In between shifts The exhaust popped a lot at lower rpms but not very loud, just moderate popping. And while cruising the car would feel like it's missing or stuttering, the first time this happened it went away after about 30 seconds. But after another acceleration the stuttering came back and took longer to go away. I'm thinking something in the carb is screwed up somehow, maybe a blown power valve or something. Also the car seemed to stall easier, pulling the car into the garage it stalled about 3 times and each time took a bunch of cranking to get it to fire back up. It's a 4 speed manual but I didn't change the way I normally work the clutch so something is messed up. I set the timing to 36 total advance, I don't know how to set or check initial timing. I'll investigate for any issues tomorrow.

Thanks for all the help

derekderek

it is. Not closed all the way till probably 20 deg ATDC. 230 deg exhaust duration at .050. 180 is BDC to TDC. The other 50 is opening on the way down on power stroke, and closing on the way down on intake stroke.

HeadsU.P.

I guess I am not following you. The only way there would be a vacuum in the exhaust system would be when a EXH valve is open on the downward cycle of the piston.
See post # 23

68post

I've never seen nor heard of a problem so severe that you could pull a Vacuum the entire length of the exhaust all the way to and into a cylinder, nor a vacuum at all from an open exh valve.

You can pull air into the exh pipe by way of a leak somewhere along the length of the exh, but not from the tailpipe to the cyl itself. Too much other exhaust gases unless it has individual pipes (zoomies).
One downward stroke is with the intake valve open and the other is the power stroke.

BakedPotato65

Well so far the engine runs fantastic, but still has exhaust popping around 3000rpm. I checked all of the exhaust valve pushrods and none of them seemed tight, they all spun about the same. So I'm assuming that the heads might be damaged I'm some way because the engine did overheat a couple times a while back, once from a suck thermostat and another time from throwing all the belts.